Certain embodiments of the present invention generally relate to a connector system that electrically connects components to one another and more particularly relate to plug and block connectors connecting contacts arranged in differential pairs.
Various electronic systems, such as those used to transmit signals in the telecommunications industry, include connector systems that electrically connect differential pairs of wires with each other. The telecommunications industry uses differential pairs of twisted wires where one wire in each differential pair carries a positive signal and the other wire carries an inverse signal. The differential pair does not include a ground, but instead carries signals intended to have the same absolute magnitude, yet opposite sign. The connector systems include an insulated connector plug and an insulated connector block that connect two separate sets of wires extending from electronic components. The connector plug receives a cable carrying differential pairs of wires. The cable is held in the connector plug. The wires are separated from the cable and each differential pair is untwisted at a neck of the connector plug. Each wire is then carried in a channel to a termination point.
The connector block has a bottom end that receives separate differential pairs of wires. The connector block carries differential pairs of block contacts, while the connector plug carries differential pairs of plug contacts. The plug contacts have first ends configured to engage the wires at the termination points. The block contacts have first ends configured to engage the wires at the bottom end. The block contacts have second ends that have catches configured to engage wires or other contacts. The plug contacts have long crossbeams that intersect at second ends. The catches in the block contacts engage the crossbeams of the plug contacts. Block contacts in a differential pair in the connector block engage corresponding plug contacts in a differential pair in the connector plug. One set of engaging plug and block contacts in a differential pair connect two wires that carry the positive signal. The other set of engaging plug and block contacts in a differential pair connect two wires that carry the negative signal.
However, conventional connector assemblies have several drawbacks. First, the contacts of adjacent differential pairs (within either the connector block or the connector plug) are positioned proximate each other such that unwanted electromagnetic (EM) signal coupling, or cross talk, develops between the contacts of the adjacent differential pairs. The cross talk degrades the quality of the signal transmissions such that the electrical signals may not be deciphered at their destination.
Some connector assemblies have been proposed that afford EM shielding by providing metal divider shields between the differential pairs of contacts. The divider shields act as barriers to electrically isolate the differential pairs of contacts and prevent unwanted EM signal coupling between contacts of adjacent differential pairs. The EM signals cause the divider shields to collect a capacitive charge. Conventional connector assemblies discharge the capacitive charge by connecting the divider shields to ground or interconnecting all of the divider shields such that the charges collected on the divider shields negate each other. However, the divider shields only partially surround the differential pairs of plug and block contacts, and thus differential pairs of plug and block contacts are not fully isolated from charges created by separate differential pairs of plug and block contacts. Also, the divider shields take up extra space within the plug and block connectors and can be difficult to connect to a ground because they are inserted inside of the connector plug and the connector block.
Further, both the plug and block contacts have different geometries from the wires. The difference in geometry creates differences in impedance for differential pairs of plug and block contacts as compared to the impedance of the differential pairs of wires. This impedance mismatch causes a portion of the electrical signals to be reflected at the connector back onto the wires toward the signal source. The amount of signal reflection that occurs due to an impedance mismatch is termed a return loss.
Furthermore, the wires of a differential pair are separated or untwisted at the neck of the connector plug and extend along individual parallel channels to the termination points. The parallel channels in the neck of the connector plug add excess space and length to the connector. When routing the wires, each wire may be terminated at a different length from the neck or may be misrouted causing the wire to be incorrectly terminated at the plug contact. Additionally, depending on the wires and the application, wires in a differential pair should have a predetermined number of twists within a given length of the wire. Controlling the twists per unit of length improves the EM coupling between the wires in a differential pair and inhibits a wire in one differential pair from becoming EM coupled to a wire from an adjacent differential pair. Therefore, untwisting the wires of a differential pair for the distance from the neck to the termination points increases cross talk among the differential pairs of wires.
In certain industries, standards are set for performance requirements of electrical connector assemblies, including a bandwidth for the transmission of signals. New standards have increased the maximum frequency of the bandwidth such that many conventional connector assemblies exhibit unacceptable levels of cross talk and return loss to meet the more stringent frequency requirements.
Thus, a need exists for a connector assembly that reduces cross talk and return loss in a connector system holding multiple differential pairs of contacts.
Certain embodiments of the present invention include a connector plug having a plug body holding multiple contacts arranged in at least one differential pair. The contacts extend along a vertical axis of the plug body. The connector plug also includes a wire guide having a first end configured to join an end of the plug body. The wire guide has a second end configured to receive a cable containing differential pairs of adjacent wires. The wire guide has guide slots and each guide slot carries a corresponding differential pair of wires. The first end of the wire guide includes channels that open onto the second end to receive the contacts. The second end has wire dress grooves extending from the guide slots to the channels. Each of the wire dress grooves receives a single wire.
Certain embodiments of the present invention include a connector plug having a housing guide formed along a longitudinal axis. The housing includes channels that open onto a bottom end of the housing to receive contacts. The channels are grouped in differential pairs including first and second channels located on a common side of the longitudinal axis adjacent differential pairs of channels being located on opposite sides of the longitudinal axis.
Certain embodiments of the present invention include a connector having a housing with a channel extending therethrough between first and second ends of the housing. The connector includes an insert carrying contacts arranged in a differential pair. The channel receives the insert and positions the contacts in a predetermined orientation. The housing is at least partially covered with a conductive substance to shield the differential pair of contacts.